Privacy

Last updated: November 4, 2026 · This is a translation. If the two differ, the German version applies: https://gymbutt.ch/datenschutz.html

Who is responsible?

Moritz Härri Rainstrasse 31, 8038 Zurich, Switzerland gymbutt@outlook.com

This policy applies to the iPhone app GymButt, including beta versions on TestFlight, and to the website gymbutt.ch. It follows the Swiss Federal Act on Data Protection (FADP) and, where applicable, the EU General Data Protection Regulation (GDPR).

In short

  • Without Butties and without Strava, your workout data never leaves your iPhone.
  • You only need an account if you use Butties (groups with friends).
  • Workouts, weights, body weight, nutrition, steps, cardio from Apple Health and notes stay on your iPhone. Two exceptions, both optional: with Butties, a few details go to your group, for example your set count for the weekly challenge. When you send a workout to Strava, exercises, sets, reps and weights go to Strava.
  • There are no ads, no tracking and no analytics tools, neither in the app nor on the website.
  • We don't sell data and only share it with the service providers listed below.
  • You buy GymButt Pro through Apple. We never see payment details.

Data the app stores only on your iPhone

  • Workouts: exercises, sets, reps, weights, rest times, workout templates and weekly plan.
  • Progress: XP, level, streak, unlocked rewards and how your avatar looks.
  • Nutrition profile: diet (vegan, vegetarian, everything), body weight, goal, meals per day and favorite recipes.
  • Exercise photos: if you add a photo from your library to an exercise, GymButt copies it into the app's own storage on your iPhone. GymButt only accesses the pictures you pick, never the camera, and doesn't upload them anywhere.
  • Settings: language, units, reminders.

We have no access to this data. If you delete the app, it is gone. Exception: a backup of your iPhone via iCloud or a computer, which is covered by Apple's terms. A Butties account is not deleted when you delete the app. Delete it first in the settings (see below), otherwise we delete it automatically after 12 months without use.

Butties (groups with friends)

Butties is optional. Nothing is transferred unless you sign in.

Sign-in: you sign in with "Sign in with Apple". We receive a random user ID. We don't get your name or email address (the app doesn't request them from Apple). For sign-in, Firebase Authentication (Google) stores this user ID and the time it was created and last used.

What is stored on the server:

  • the nickname you choose (up to 20 characters),
  • how your Butt looks (fur color, worn items and their colors), your level and your streak, plus when this was last updated,
  • whether you trained today, have a rest day or are still open, and for the last 2 and the next 7 days only these three states (trained, rest day, open). The server uses this to calculate your group's shared streak. It stores per group and day who trained, had a rest day or was open, and deletes these days after 30 days,
  • your groups: group name, members, since when someone is a member, and the invite code,
  • group activity: short entries like "Lea joined", "Ben is cheering Lea on" or "Challenge completed". They are deleted after 90 days,
  • cheers: who cheered whom on which day (for the "once a day" limit, deleted after 2 days),
  • for notifications, a Firebase Cloud Messaging (Google) device token and the app language. Only the server can use it to send you a notification ("Lea is cheering you on"). You can turn notifications off in the settings under Butties, which deletes the token,
  • for the weekly challenge exactly one number per person, for example "12" (leg sets this week), "2" (workouts) or "35" (minutes of cardio). Individual sets, weights or reps are not included. Challenges are deleted after 8 weeks,
  • workout templates you send to a Buttie or a Buttie sends to you: template name, exercise names and set counts, sender and recipient. They are deleted as soon as the recipient accepts or declines them, at the latest after 30 days. Only people from your groups can send you something. If you share a template with a whole group, all members can see it until you remove it, leave the group, delete your account or 30 days have passed,
  • wrong invite codes: how often you entered a wrong code in the last 24 hours. After 10 failed attempts, joining is blocked for 24 hours so nobody can guess codes. The counter is deleted after one day.

What doesn't go to Butties: weights, individual sets and reps, your workout history, body weight, nutrition, steps and other health data, notes and workout times. From your training, only the daily status (trained, rest day, open) and the one challenge number are shared.

Who sees it: only members of your groups see your nickname, your Butt, your level, your streak, your daily status and your challenge number. There are no public profiles and no way to search for people. A group has at most 6 members. Anyone who knows an invite code can join the group, so only give it to people you want in the group. The code is valid for 14 days and can be renewed at any time, which makes the old one invalid. Expired codes are deleted 30 days after they expire.

Deleting: in the settings under "GymButties" you can delete your Butties account at any time. This immediately deletes your sign-in, profile, memberships, entries, challenge numbers and all templates you sent or received from the server. Groups without members are deleted too. If you owned a group, it passes to another member. Your workouts on the iPhone stay.

Inactive accounts: if you haven't opened GymButt with a Butties account for 12 months, we delete the account automatically in the same way.

Backups: so nothing is lost after an error, Google Firebase makes a daily backup of the database, also in the Zurich region. Each backup is deleted after 98 days, so deleted data also disappears from the backups at the latest 98 days later. We only use them to restore the database after an error.

GymButt Pro (subscription)

GymButt Pro is an optional subscription you buy in the app through Apple (in-app purchase).

  • Payment: purchase, payment, renewal and cancellation run entirely through your Apple account. We receive neither your name nor your email address nor payment details. Apple's privacy policy applies.
  • Check in the app: at launch the app asks Apple (StoreKit) directly on your iPhone whether a subscription is active and only remembers "Pro active" or "not active", so Pro also works offline. There is no server of our own for this, and the purchase is not linked to a Butties account.
  • What we see: Apple provides aggregated sales and subscription figures in App Store Connect (for example the number of subscriptions per country). We cannot identify individual people from them.
  • Cancel: cancel at any time in iOS Settings under your name > Subscriptions, at least 24 hours before it renews. "Restore purchases" brings an existing subscription to a new device.

Apple Health (steps and cardio workouts)

If you allow it, GymButt reads your step count from Apple Health. The app only uses it to check whether you reached your daily goal and to give you XP for it. GymButt doesn't write anything to Apple Health. The step count doesn't leave your device and is not used for advertising. If you turn on "Cardio from Apple Health" in the settings, GymButt also reads your workouts (type, time, duration and distance of running, cycling, swimming and similar activities, never strength training, heart rate, route or energy) and stores them in your history on the iPhone. This data doesn't leave your device either; Butties only receive at most the status "trained today" and, if the weekly challenge counts cardio minutes, your number of minutes. You can revoke access at any time in the Health app or under Settings > Privacy > Health.

Strava (send workouts to Strava)

Strava is optional. Nothing is sent to Strava unless you connect it.

  • Connecting: you sign in to Strava with your own Strava account and only allow GymButt to upload activities ("activity:write"). GymButt cannot read data from your Strava account, except the account name Strava returns at sign-in, which the app displays.
  • What goes to Strava: only when you send a workout to Strava: workout name, start time, duration and the exercise list with sets, reps and weights as text. The app sends this directly from your iPhone to Strava, not through our server. No pictures or other health data are sent.
  • Image in Photos: Strava doesn't let other apps attach images to activities. That's why GymButt saves the workout image (muscle map and exercises) to your photo library when sending, so you can add it in Strava yourself. iOS asks once for the "Add Photos" permission. With it, GymButt can only add pictures and cannot see your other photos.
  • Credentials: the access tokens are stored encrypted in your iPhone's keychain. To exchange the sign-in code for tokens and to renew them, a request goes through our server at Google Firebase (Cloud Functions, Zurich region), because this needs a secret key that must not be in the app. The server passes the code to Strava and returns the tokens to the app. It doesn't store the code or tokens and doesn't write them to logs. You don't need a Butties account for this.
  • At Strava: Strava (Strava, Inc., USA) is responsible for your data on Strava itself. Strava's privacy policy and terms apply (https://www.strava.com/legal/privacy). What is visible on Strava is controlled by your Strava settings.
  • Disconnecting: you can disconnect Strava in the settings at any time. GymButt then revokes access at Strava and deletes the tokens from the iPhone. You delete activities you already sent directly on Strava. You can also revoke access at strava.com > Settings > My Apps.

Notifications and Live Activities

The rest timer, cooking timers, workout reminders and the workout display on the Lock Screen are local notifications. They are created on your iPhone and no data is sent for them. You can turn them off in iOS Settings.

Butties notifications ("Lea is cheering you on") are sent by our server through Firebase Cloud Messaging (Google) and Apple's push service to your iPhone. Your device token and the notification text with the nickname of the person cheering you on go to these services.

Sharing a workout image

When you share a workout, GymButt creates an image with the muscle map and exercises on your iPhone. You choose where it goes (e.g. Instagram, Messages or "Save Image") in the iOS share sheet. GymButt doesn't send the image anywhere on its own.

Import and backup

When you import a CSV file (e.g. from Strong or Hevy) or export a backup, this happens through the iOS file picker or share sheet. You decide where an exported file goes.

TestFlight

If you test GymButt via TestFlight, Apple provides us with: your email address (if we invited you by email), your name (if you provided it), installation date, device model, iOS version, crash reports and feedback you send through TestFlight. We only use this to improve the app and invite you to the beta. We delete it at the latest one year after the beta ends. Apple's privacy policy also applies: https://www.apple.com/legal/privacy/

Contact by email

If you write to gymbutt@outlook.com, we process your email address and the content of your message to reply. The mailbox is hosted by Microsoft (Outlook.com), which may also process the data in the USA. We delete emails once the matter is settled and we no longer need them, at the latest after 2 years.

Website gymbutt.ch

The website sets no cookies, uses no analytics tools and loads no fonts, scripts or content from third-party servers. There are no forms.

It is hosted on GitHub Pages (GitHub, Inc., USA, a Microsoft company). When you open a page, GitHub processes technically necessary data such as your IP address, the requested page, date and time, and browser and operating system to deliver the page and protect it from attacks. We don't receive this data ourselves. GitHub's privacy statement applies: https://docs.github.com/en/site-policy/privacy-policies/github-general-privacy-statement

The invite page (gymbutt.ch/join.html) shows a Butties code from the link. The code stays in your browser and is not passed on to other sites.

Service providers and transfers abroad

We work with these service providers. They process data on our behalf or, like Apple and Strava, under their own responsibility when you use their services:

  • Google Firebase (Google Cloud EMEA Ltd., Ireland, and Google LLC, USA): database (Cloud Firestore) and server functions (Cloud Functions) in the Zurich region (europe-west6). Firebase Authentication and Firebase Cloud Messaging are global Google services and may also process data in the USA. We don't use Firebase analytics services (Google Analytics, Crashlytics).
  • Apple (Apple Distribution International Ltd., Ireland, and Apple Inc., USA): App Store, in-app purchase, TestFlight, Sign in with Apple and push notifications.
  • Strava, Inc. (USA): only if you connect Strava.
  • GitHub, Inc. (USA): website hosting.
  • Microsoft (Ireland and USA): email mailbox.

For transfers to the USA we rely on Google, Apple, Microsoft and GitHub being certified under the EU-U.S. Data Privacy Framework and the Swiss-U.S. Data Privacy Framework, and on the European Commission's Standard Contractual Clauses offered in these providers' terms.

Server logs

When the app talks to our server (only with Butties or when connecting Strava), Google Cloud logs technical details of each request: time, function called, duration, errors and, depending on the service, the IP address and device model or app version. We only use these logs to find errors and prevent abuse. Google deletes them after 30 days. We don't write content such as Strava tokens to the logs.

Legal bases (GDPR)

Where the GDPR applies, we process data on these bases:

  • Contract (Art. 6(1)(b)): Butties, GymButt Pro and replying to your emails, because you want to use these features.
  • Consent (Art. 6(1)(a) and Art. 9(2)(a)): Apple Health, Strava, push notifications, Photos and TestFlight. You give it by turning on the feature or confirming the iOS permission, and you can withdraw it at any time (see each section above). Withdrawal applies from then on; earlier processing remains lawful.
  • Legitimate interest (Art. 6(1)(f)): server logs, blocking wrong invite codes and delivering the website, so everything runs securely and reliably.

Children

You can use GymButt without Butties and without Strava at any age, because then no data comes to us. Butties and Strava are meant for people aged 16 and over. If you are younger, ask your parents first. If we learn that a Butties account belongs to a child under 16 without this consent, we delete it.

Health notice

Calorie and protein targets in GymButt are rough guidelines. They don't replace medical or nutritional advice.

Your rights

You have the right to:

  • Access: what data we have about you,
  • Rectification of incorrect data,
  • Erasure: you delete your Butties account yourself in the app under Settings > GymButties. For anything else, for example TestFlight details or emails, write to us,
  • Restriction of processing,
  • Data portability: you export your workouts yourself as a backup in the app. We send you your Butties data on request in a common format,
  • Objection to processing based on legitimate interest,
  • Withdrawal of consent, at any time and for the future.

Write to gymbutt@outlook.com for this. Since GymButt doesn't send your workout data to us, these rights mainly concern Butties data, TestFlight details and emails with us. Apple, not we, holds the data on purchases and subscriptions.

You can also complain to the Swiss Federal Data Protection and Information Commissioner (FDPIC, https://www.edoeb.admin.ch) or to a data protection authority in the EU, for example in your country of residence.

EU representative

GymButt has no establishment in the EU. We have not appointed a representative under Art. 27 GDPR because we only process data of people in the EU occasionally and on a small scale, and no extensive health data comes to us. Please contact us directly at gymbutt@outlook.com with any questions.

Changes

When GymButt gets new features that process data, we update this policy beforehand. The current version is always at https://gymbutt.ch/en/privacy/.